1. Field of the Invention
The present invention relates to a surface acoustic wave device including a piezoelectric substrate and interdigital transducer (IDT) electrodes on a surface of the piezoelectric substrate.
2. Description of the Related Art
Hitherto researchers have created various surface acoustic wave devices that have a piezoelectric substrate and an IDT electrode on the surface of the piezoelectric substrate. For example, Japanese Unexamined Patent Application Publication No. 2006-270906 discloses a surface acoustic wave device that has a piezoelectric substrate and a plurality of electrode fingers partially embedded in the thickness direction so as to stick out or protrude from the surface.
Japanese Unexamined Patent Application Publication No. 2006-270906 mentions that various known piezoelectric substrates and materials for electrode fingers can be used, and also specifies the required depth of grooves in which the electrode fingers are formed and the required uniformity of the thickness of the electrode fingers.
Selecting the material for the electrode fingers and the depth of the grooves in accordance with the requirements specified in Japanese Unexamined Patent Application Publication No. 2006-270906, however, can lead to poor characteristics of the surface acoustic wave device because the performance parameters of the device, e.g., the band width ratio, the resonance Q factor, and the spurious characteristics, vary with the combination of the material for the piezoelectric substrate and that for the electrode fingers.